Preparation of useful building blocks, α-iodo- and bromoalkanols from cyclic ethers using the Dowex H<sup>+</sup>/NaX (X = I, Br) approach
作者:Petri A. Turhanen、Jouko J. Vepsäläinen
DOI:10.1039/c5ra20813k
日期:——
reported novel green chemistry tool was effectively used for opening cyclic ethers to produce α-iodo- and bromoalkanols. The synthesis of 4-iodobutanoic acid from γ-butyrolactone has also been described. The method is based on the use of a dried Dowex H+/NaX (X = Br, I)-system, which is effective at producing α-iodoalkanols and some α-bromoalkanols from commercially available cyclic ethers. Additionally
我们最近报告的新型绿色化学工具有效地用于开环醚以生产α-碘和溴代链烷醇。也已经描述了由γ-丁内酯合成4-碘丁酸。该方法基于使用干燥的Dowex H + / NaX(X = Br,I)系统,该系统可有效地从可商购的环状醚生产α-碘代链烷醇和某些α-溴代链烷醇。另外,证明了打开三种不同的冠醚以形成具有各种链长的α-碘(聚乙烯)二醇。卤代链烷醇是合成化学中重要的组成部分,例如用于药物化学目的。
Bifunctional silanol-based HBD catalysts for CO<sub>2</sub> fixation into cyclic carbonates
First examples of unprecedented silanol-based bifunctional HBD catalysts [(tBuO)2(N(CH2CH2)3N)CH2CH2O}Si(OH)]+I− and (Rac)- and (R)-[(tBuO)2(N(CH2CH2)3N)CH2(Et)CHO)}Si(OH)]+I− with tetraalkylammonium units directly incorporated into their structures were prepared from tailor-made silanols. These bifunctional silanols were used together with other mixed alkoxysilanols of general formula (tBuO)2(RO)SiOH
Novel Nucleophilic Trifluoromethylation of Vicinal Diol Cyclic Sulfates
作者:Naoto Takechi、Samia Ait-Mohand、Maurice Medebielle、William R. Dolbier
DOI:10.1021/ol0270374
日期:2002.12.1
[reaction: see text] A novel method for highly regioselective and stereospecific nucleophilic trifluoromethylation of vicinal diol cyclic sulfates, using the reagent derived from reduction of trifluoromethyliodide by tetrakis(dimethylamino)ethylene (TDAE), is presented.
Exploratory Studies on Reactions of Cobaloxime π-Cations with C-Nucleophiles: Irreversible Alkene Decomplexation versus Nucleophilic Capture
作者:Jennifer L. Gage、Bruce P. Branchaud
DOI:10.1021/jo951319i
日期:1996.1.1
(beta-Hydroxyalkyl)- and (beta-acetoxyalkyl)cobaloximes can undergo facile acid-catalyzed P-heteroatom exchange with oxygen and nitrogen nucleophiles in an S(N)1-like mechanism via cationic metal-alkene pi-complex intermediates (cobaloxime pi-cations). The reaction of cobaloxime pi-cations with carbon nucleophiles has not been previously reported. The results reported in this paper demonstrate that cobaloxime pi-cations are reasonably good electrophiles. They are sufficiently reactive to add to the electron-rich sp(2) centers in allyltrimethylsilane and pyrrole. A major side reaction for intermolecular reactions is irreversible alkene decomplexation. An intramolecular pyrrole cyclization (22 to 23, 83% yield) significantly raised the yield for nucleophilic addition compared to that of the analogous intermolecular couplings (12b tb 13b, 32% yield and 17 to 18, 29% yield). The results of these studies provide a foundation for the design and evaluation of modified cobalt ligands with the goal of suppressing alkene decomplexation and enhancing reaction of cobaloxime pi-cations with C-nucleophiles.